# Wetted Perimeter

Wetting perimeter is the portion of the channel that is in contact with the fluid flowing.

## Wetted perimeter formulas

\(\large{ P_w = \frac{ A_c }{ r_h } }\) | |

\(\large{ P_w = 2 \; h \; \sqrt {1 + z^2 } }\) | (hydraulic radius) |

\(\large{ P_w = r \; \theta }\) | (Hydraulic Radius of a Partially Full Pipe (Less than Half Full)) |

\(\large{ P_w = 2 \; \pi \; r - r \; \theta }\) | (Hydraulic Radius of a Partially Full Pipe (More than Half Full)) |

### Where:

\(\large{ P_w }\) = wetting perimeter

\(\large{ A_c }\) = area cross-section of flow

\(\large{ \theta }\) (Greek symbol theta) = degree

\(\large{ h }\) = depth of fluid

\(\large{ r_h }\) = hydraulic radius

\(\large{ \pi }\) = Pi

\(\large{ r }\) = radius

\(\large{ z }\) = width of channel slope

Tags: Equations for Hydraulic